HighDPI and Qt Designer

I am using Qt designer for creating dialogs in my application. Everything looks fine on normal display but on 4K with 200% in Windows DPI setting dialogs and elements are too small. I expect that when I set layout margins to 6 to have it 12, when I add spacer on 40 pixels it would be 80 and when I set 400x300 dialog size it would be 800x600. Same for minimum/maximum size, etc. Is there a way to achieve such results with current Qt version (I am using 5.5.1)?